h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

When we see the sun and the moon together (say by evening before sunset, in november, in india), how come the moon is not in its full size? Logically, wont the sun's rays be lighting up the visible part of moon, fully?

Traveller in Time on his head
"Go sit in the sun, well any bright spotlight will do.
Take a ball in one hand an armlength away, move it from the shadow of your head around your head toward the light source. See the shadow growing ? "

If the moon were a flat disc, then it would be either completely white all over the side we see, or completely dark. But because the moon is a sphere and only one side of it is lit by the sun, we can see it in various ways.

When the moon is between us and the sun, we see only a narrow crescent, as we are looking mainly at the dark side. When the moon is opposite the sun, then we see mainly the bright side, so it is nearly a perfect circle. When it is exactly opposite the sun, the sun and the moon won't be in the sky at the same time; this is full moon.

do u mean to say this happens because of earth's shadow??

No it is the moon's shadow on itself.

Traveller in Time on a shooting star (tonight)
"How about its own shadow?




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The moon will cast its own shadow over its own rear side
"

I know what you mean about when they are both in the sky at the same time then there is no shadow from the earth.

But it is because of the relative distance from the earth. The moon is so close compared to the sun that the suns rays cant 'bend' in front of the moon (to the face we see) to light it up as in a full moon. So we still only see a crescent moon or half moon etc. The sun can light up some of it depending on how big the angle between the moon and the earth and the sun and the earth

thank you all... i got the point now..